var x = [30, 40];
console.log([10, ...[], 20, ...x, 50]["length"]);
console.log([10, ...[], 20, ...x, 50][0]);
console.log([10, ...[], 20, ...x, 50][1]);
console.log([10, ...[], 20, ...x, 50][2]);
console.log([10, ...[], 20, ...x, 50][3]);
console.log([10, ...[], 20, ...x, 50][4]);
console.log([10, ...[], 20, ...x, 50][5]);
